JSON ↔ YAML ↔ TOML Converter
Convert between JSON, YAML, and TOML; reformat each one cleanly; and get precise line and column diagnostics when something is wrong.
Examples
Source
Target
Diagnostics
Structural summary
How it works
The converter parses your input with a battle-tested library — native JSON for JSON, js-yaml for YAML, smol-toml for TOML — and re-serializes it in the target format. Inputs over 200 KB are processed in a Web Worker so the page stays responsive.
Lossy conversions
The three formats overlap a lot but not completely. YAML allows comments and anchors; TOML cannot represent null or arrays of mixed types; TOML output also requires an object at the root. The diagnostics panel surfaces these cases instead of failing silently.
Edge cases and notes
- Comments are preserved only by the source format's parser. Round-tripping comments across formats is not always possible.
- YAML's flexible scalar types (e.g.
yesas boolean) follow the default schema. Quote strings that look like booleans or numbers if you want them as text. - TOML datetimes use the RFC 3339 format. JSON has no datetime type, so dates round-trip as strings.
FAQ
Is my input sent anywhere?
No. Parsing and conversion happen in your browser. The page does not call any backend.
Why does my TOML conversion fail with a "top-level" message?
TOML cannot have an array or scalar at the very top. Wrap your value in an object before converting.
Why did my YAML strings change quoting style?
The serializer picks the safest quoting style automatically. Functionally the result is equivalent. If you need byte-identical output, edit by hand after the conversion.